This invention relates to a corner guard for a box spring or mattress foundation.
The term box spring or mattress foundation is commonly used to describe any mattress support system. Conventionally, the corners of a box spring construction are stuffed with foam, cotton, or scraps of other fibrous material to pack the corners to give a suitable and attractive upholstered finished product. Often these conventional materials and stuffing methods are inadequate to keep the corners of box springs filled and contoured during use and handling. Consequently, such conventional materials and stuffing methods may allow the corners of the box springs to become concave during use and handling.
In addition, conventional materials and stuffing methods may result in manufacturing inefficiencies. Because the conventional materials used for stuffing the corners of a box spring are compressible fillers, the compressibility of the fillers may result in a corner being understuffed for the size of the perimeter border. For example, when a perimeter border is cut too small, an assembler may be unable to pack the corners with an acceptable level of material, and the box spring upholstery must be removed and box spring remanufactured.
The prior art has addressed the problem of box spring corners. Callaway U.S. Pat. No. 5,265,291 assigned to Simmons Company, the assignee of the present invention, discloses a box spring with a corner support. The corner support is made of resilient plastic and includes two snap fitting flanges at the top end of the corner support. The snap fitting flanges of the corner support engage the border wire of the box spring. In one embodiment, the bottom end of the plastic support maybe left unattached to the base of the box spring so that the bottom end of the plastic support floats as the wire grid and border wire move toward and away from the base of the box spring. In another embodiment, the corner support is stapled to the wooden base of the box spring and is plaited so that the plaited portion of the corner support can provide flexibility to the corner support and thereby accommodate the relative movement between the wire grid and the base of the box spring.
While the Callaway patent solves many of the problems associated with stuffed corners on a box spring, the snap fit attachment of the corner support to the border wire implicates other issues that may require improvement. For example, when a fibrous top pad is placed over the wire grid in the Callaway box spring, the fibrous top pad is wrapped around the corner support. Because the fibrous top pad is wrapped around the corner support and because the fibrous top pad must be attached to the border wire, an unsightly bulge results at the four corners of the box spring. Alternatively, the fibrous top pad could be cut to fit the outside dimensions of the border rod. This approach used in conjunction with the Callaway corner support would, however, add cost to the fibrous top pad, be more challenging to manufacture, and compromise quality because the border wire would no longer be wrapped by the fibrous top pad. The snap fit of the corner support in the Callaway prior art reference also requires that the material for the corner support be a resilient or flexible plastic material where other nonresilient materials might otherwise be more attractive from a cost standpoint. Moreover, the Callaway snap fit corner support creates a non-uniform top surface with two bumps at each corner where the snap fit flanges engage the border wire. The Callaway snap fit corner support also requires that the border wire be of a known and constant diameter and that the corner of the border wire be free of any crosswires of the wire grid. Finally, the Callaway snap fit corner support requires a repetitive finger pinch force action during the manufacturing process. Ergonomically, repetitive finger pinch movements by installers should be avoided.
The box spring corner guard of the present invention addresses the problems associated with stuffing box spring corners as well as the issues associated with the prior art resilient plastic box spring corner supports. Particularly, the box spring corner guard of the present invention has been designed to replace conventional materials used to pack and fill the corners of a box spring and to improve upon the prior art resilient plastic corner support.
The box spring corner guard of the present invention is adapted for use with a box spring having a base, typically a wood lattice, and a wire grid supported by means of upright wire supports. Such a box spring has a border wire extending around the periphery of the wire grid. The border wire is connected to the crosswires of the wire grid and to the upright supports.
The box spring corner guard of the present invention comprises a curved body having the shape of a 90 degree section of an imaginary cylinder. The curved body has a concave inner surface and a convex outer surface. The curved body has a bottom end and a top end. The length of the curved body extends in a direction parallel to the axis of the imaginary cylinder that defines the shape of the curved body. A locator flange extends from the concave inner surface adjacent the bottom end of the curved body. Strengthening ribs run along the length of the curved body to add rigidity to the curved body. In one embodiment, the curved body also has a limit flange, similar to the locator flange, extending from the concave inner surface adjacent the top end of the curved body.
When incorporated into a box spring to serve as a corner guard, the bottom end of the curved body is attached to the base of the box spring by means of staples, nails, screws, rivets, adhesives, or like at one of the corners of the box spring. The locator flange provides a seat for the corner guard on the base of the box spring to limit relative movement between the corner guard and the base of the box spring in a direction parallel to the length of the curved body. The top end of the curved body extends to a position adjacent the border wire. The top end of the curved body is not attached to the border wire, and a small space exists between the border wire and the concave inner surface of the curved body so that the fibrous top pad covering the wire grid can be tucked between the border wire and the corner guard and attached to the border wire. Because the fibrous top pad covering the wire grid can be tucked between the border wire and the corner guard, the corner guard of the present invention provides a smooth corner finish adjacent to border wire without bulges either on the convex outer surface of the curved body or on the top of the border wire. Moreover, the strengthening ribs along the length of the curved body provided rigidity so that the corner guard is not easily deflected inwardly during use and handling, thus maintaining a smooth concave upholstered surface at the corner of the box spring.
In another embodiment of a corner guard of the present invention, a limit flange is located on the concave inner surface of the curved body adjacent the top end of the curved body. The limit flange is therefore position below the border wire so that movement of the border wire toward the base of the box springs will cause the border wire to contact the limit flange and thus limit relative movement of the border wire toward the base of the box spring. The strengthening ribs along the length of the curved body provide rigidity so that the corner guard with the limit flange can support the corner of the wire grid from deflection toward the base of the box spring.
Therefore, it is an object of the present invention to provide a box spring corner guard that has an appropriately sized full quarter round radius at the corner of the box spring to ensure a smooth fit of the upholstery at the corner of the box spring.
It is also an object of the present invention to provide a box spring corner guard that, because of uniform shape, lessens the degree of accuracy required when sizing the perimeter band or border of the box spring.
Moreover, it is an object of the present invention to provide a box spring corner guard that is rigid enough to withstand being deflected inwardly as a result of ordinary use and handling of the box spring.
Further, it is an object of the present invention to provide a box spring corner guard that is sufficiently rigid to support the border wire and limit deflection of the border wire toward the base of the box spring.
Further objects, features and advantages will become apparent upon consideration of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.